Automatic reversing system for telegraph circuits



June 12, 1928. 1,673,445

W. A. DUDLEY AUTOMATIC REVERSING SYSTEM FOR'TELEGRAPH CIRCUITS Fild March 17, 25

gvwmltox V WA.,DudZey' Patented June 12, 1928.

WILLIAM A. DUDLEY, OI BROOKLYN, NEXV YORK, A

TELEGRAPH COMPANY, OF YORK, N. Y.,

NT OFFICE.

, ssrenoa TO THE WESTERN UNION A conronn'rron ornnw YORK.

AUTOMATIGREVERSING S YSTEMFOB TELEGRAPH CIRCUITS.

Applicationfiled March 17, 1925. i SerialNo. 16193..

My invention relates generally to cabletee legraphy. Specifically, it concerns a method. for automatically and periodicallyreversing the direction of operationof a simplex. cable circuit and is intended to apply in cases.- where duplex operation is impracticable.

In a cable system the sending apparatus consists of a motor driven transmitter which, by means of a perforated tape, is caused to send to the cablethe code signals consisting of dots, dashes and spaces. The receiving apparatus is essentially a sensitive galvanometer with its armature arranged to con.-

trol an ink siphon in contact with moving tape. The impulses from the cable passing through the galvanometer cause this siphon to move, thus recording the signals in: the form of undulations on thetape.

The dots and dashes forming the codeare of equal length butare opposite in polarity. Spaces? are periods of no current, and, be-- tween letters, are made the samelength as a ill dot e. one unit). Spaces betweenwords; however, are-made three times aswlong as I the spaces between letters (i. e. 3 units).

It is obvious that the end of a Word is a logical time for reversing the direction of operation, and the long space following aword forms a ready means of selecting the.

moment for switchingto take place. F

It is an object of my invention to provide such a selecting means which. shall operate,

to initiate the switching operations, at a mo ment when the long space followings. word occurs. 6

In particular, I contemplate the provision of selecting means at the transmitting station automatically responsive to a no current conditioner? the line lasting for an interval greater than one unit, and selecting means at the receiving station responsive-only after an intervalgreater than three units- It is also an important object of my invention to cause the switching to take place automatically and at will, that is, to permit transmission in a given direction to continue nninterruptedly for any desired 'length of time but to automatically terminate the transmission upon: the lapse of a, predetermined time interval.

The figure shows my invention applied .With the apparatus. connected as shown: in

the drawing, station 1 is sending to station 2. Signals trom the transmitter X pass through the winding of relay A contacts T of relay B to the. cable and thence to contactsR otrelay 13,, through the winding of relay E and through ground. At station 1 the receiving apparatus is disconnected from the cable by open contactslt of relay B and at station 2 the transmitting apparatus is disconnected from the cable by open contacts T of relay B Relays B and C are energized through a circuit extending from ground ,at relay D through contacts contacts L winding or relay B winding of relay 6,, and through the local battery LE, to ground. A circuit is also completed through contacts P of relay G which energizes magnets from local battery L13 Magnet S operates to disengage the clutch .K to disconnect motor M from the transmitter X and to apply a brake (not shown). to. the trans. mitter, thus preventing it fromoperating.

Relay A as well as relay A is so adjusted that its contacts will not close except for no-currentpcriods of greater than unit length; in other words, the contacts will close on a word space but not on a letter space. Relay E as wellas'relay E is adjusted by, means of a suitable and well recorder WV to known mechanical delay to prevent contacts V from closing except on no-cu'rrent periods greater than three units in length, that I is, greater than a word space.

While signals are being transmitted from station 1, the circuits remain unchanged except that the contacts G close after, each word; however, this has no effect since the circuit is open at clock contacts H The switch operating mechanism of the clock at station 1 has previously been set to permit transmission from this station for a predetermined length of time. At the end of this time, clock contacts H close to prepare. a

circuit to energize relays B and C, from" local battery LB hoWever,.th1s circuit will disconnects the motor M from the trans mitter X and applies a brake (not shown) to the transmitter to stop the transmission. Thus, it will be noted that through the and, if a word is being transmitted at the action ofp relay A the transmission will ;be stoppedonly atthe end of a completed word,

time contacts I-I are closed, the circuits will remain othe'iwvise unaltered, and transmission ooiitiiiu'e untilf'th'e" word is com: pleted. Relayy B w opens contacts T, and closes contacts R thereby disconnecting the transmitter X, from theicableand/connect ing recorder W, to, the cable throughthe windingof relay E Relays' 'B andfl, are

locked in closed position by a holding or. locking circuit, extending fromloc'al battery LB, through contact L of-relay' "B, and contacts 0, of relayjD to ground:- The transmitter at station 1 has now" been. disthe winding of relay D 'This charging current is sufiicient to energize relay D to momentarilybrcak its icontactsO thereby causing relays B andG' to be deenergized. The lockingcircuit of relays B and G, is

opened at contacts L, and will notbeclosed' again until relay B is energized froin the' clockcircuit. lFhe opening of contacts ll and the closing of contacts T, opei'ates to switch the cable at stationfi from receiving apparatus to transmitting apparatus; "Atthe same time, opening"o't contacts Pgdeenergizes l magnet S K to engage clutch K and release the transmitterbrake, thereby:

starting the t-ransniittercX Transmission willnow-take place froiii station il to station 1, and operation ,Wlll'fiOl'lllTlHO llTl-lilS d recw tion untilthefclock at station 2*clo'ses contacts 'H, to'again reverse the'directikm. Contacts F and F are provided-on. re

" lays E, and E for the purpose 0'1 "discharging condensers Z, andiZ 'dui'inga receiving period, in order that they will be in a:- condition to draw a charging current, at the end of each receiving period, and thereby effect certain switching. operations as": described above 1 V 1 a In the above described operatiom -atithe instant contacts R, and T operate Ito switch the cable from transmitting to receiving. a cable of considerable length \Vlll' be, charged with a series ofiinpiilses which will dis-m charge: through the receiver at bothsta tions. This willinotailect the operation at station 2, except that, of course, the switching will be delayed until the discharge is completed. At station 1,.however, following this discharge there will be a prolongcd pe:

riod'of'no-c irrent, equal to the lag'of the cable, before the first vsignals transmitted from'station 2 reach station 1. i This will allow; the contacts V of relay E to close, anda momentary-- charging current i will flow through condenser Z to energize relay D and thereby break the holding circuit of relays 3 1ml C momentarily at'coiitacts 0,.

If relaysB and C were to 'become'dener gized their contacts would fallback to place station 1 again in transmitting position;

howeverain order to avoid this, the clock switch H is arranged to remain closed for a'loiiger period thanthe lag of thecable, andrelays Bfand G will be kept energized over this period by the clock circuit including contacts "H, and" G Thus, station 1 is" maintained-in receiving position until the signals from station 2 arrive, and atter'this,

relay E will not'be deenergized except for no-current periods greater than a word space.- The lag on any existing cable may be takeircarc of in this way by arrangin" contactsfI-Lto remain closed fora periot of 3 seconds; This periodfof course, may be increased .if necessary. After this pe riodhas expired, and contacts H have opened, the apparatus at station 1 will be in'condition to respond to the next pro longed no-current period, transmitted for the purpose of switching, vthrough the action ofr'el'a i gWhilia I have described my invention in connection with a simplexior single channel circuitit will be eyidentithat it isequally applicable to a multiple channel system op eratingin one direction'at. a time. Ic'laim: v 1 1L cable system in, which signals are transmitted as impulses of positive and negative sign, separated; by spacingperiods of no current,.a cable, aitransniitter connected to said cable atonestation, switching appa ratus ton; disconnecting the transmitter et- 'fectivefonly 'upon the establishment in the cable'of a no-current condition of given duration,and= means to permit the no-current condition to cause operation of said switchingoapparatus only after a clock-controlled transmission interval. V i

,2.lIna cable system in whichsignals are transmitted as impulses of positive and negative sign separated by spacing periods of no current,a cable, a transmitter'connected to said cable at one station, switching appa ratus for disconnecting the transmitter ctfectiveonly upontheestablishinent in the cable of a no-currcnt; condition of given duration, and adjustable clock-controlled means to permitthe no-current condition, to cause operation ofsaid switching apparatus after any desired predetermined transmission interval. M

3; In a cable circuit, an automatic transinitter, a. selective rclayiconnected thereto adapted to release its armataire upon the occurrence of a word space: in the automatic transmission, a switching relay and a circuit therefor including said armature when re leased, means to prevent operation of the switching relay comprising a pair of normally open contacts in sald switching c1r-- cuit, and clock-controlled means to close said contacts after a predetermined interval of transmission.

4. In a cable circuit, an automatic transmitter, a selective relay connected thereto adapted to release its armature upon the occurrence of a word space in the automatic transmission, a switching relay and a circuit therefor including said armature when released, means to prevent operation of the switching relay comprising a pair of normally open contacts in said switching circuit, and clock controlled means to automat ically close said contacts after a predetermined interval of transmission.

5. In an automatic cable circuit, an automatic transmitter including a clutch, a mag net adapted to open the clutch, control circuits for said magnet including a pair of normally open contacts, clock-controlled means for closing said contacts automatically after a predetermined transmission interval to prepare a control circuit for said magnet, and means to delay operation ofthe magnet until the occurrence of the next word space in the signal, transmission.

6. In a. cable circuit, an automatic transmitter, a selective relay connected thereto adapted to release its armature upon the occurrence of a Word space in the automatic transmission, a transmitter magnet adapted to control operation of the automatic transmitter, an intermediate relay controlling said transmitter magnet, and a circuit for the intermediate relay including the armature of the selective relay when released, and clock-controlled means to prevent operation of the transmitter magnet until after a predetermined transmission interval said means comprising a pair of normally open contacts in the circuit of the intermediate relay.

7. A cable circuit comprising a cable, an automatic transmitter connected thereto, a receiver, switching apparatus for disconnecting the transmitter and connecting the receiver to the cable, clock controlled means adapted to prepare a circuit for the switching apparatus at a predetermined moment of time, and means responsive to the signal transmission to automatically complete the prepared circuit at a predetermined instan in the signal transmission.

8. A cable system arranged for alternate operation in both directions, comprising a transmitting circuit, a selective relay'in the transmitting circuit operative to close its tomatic transmitter adapted to transmit Sig nal impulses oi both polarities and spacing impulses of zero current, a receiver circuit connected to the cable at the distant station including a selective relay responsive to a no-current condition of the cable greater than the spacing impulses, a switching relay including an armature connected to the cable and adapted upon its forward movement to break contact with the transmitter circuit,

clock-controlled means to operate the switching relay after a predetermined transmission interval, and means responsive to the operation of the distant-selective relay to disconnect the receiver circuit from the cable.

10. A cable telegraph system comprising a cable, a stationincluding an automatic transmitter and means for rendering the trans mitter inoperative to send signals over the cable, a distant station comprising a second transmitter and a switching relay in a circuit effective to maintain said transmitter inoperative, a selective relay at the distant station adapted to release its armature upon failure of transmission from the first station, a control relay comprising an armature contact in the switching relay circuit and.

means to momentarily energize the control relay by way of a circuit including the armature contact of the selective relay.

11. An automatic telegraph system comprising a cable extending between two stations, an automatic transmitter and a receiver at each station, an automatic reversing switch [for each station adapted to reverse the direction of operation of the cable, and control apparatus for said switch compris ing a selectiverelay in the transmitter circuit, a second selective relay in the receiver circuit, a control relay under the control of said second selective relay, a switching relay, an energizing circuit for said switching relay under control of the first selective re lay, and a locking circuit for said switching relay under control of said second selective and control relays.

In testimony whereof I aifix my signature.

WILLIAM A. DUDLEY. 

